Air filter



Oct. 24, 1961 J. J. KLEIN AIR FlLTER Filed Aug. 5, 195? lu/@3507," @ZYAQO United States Patent @nice 3,@5,516 Patented Got. 24, i961 3,005,516 AR FELTER Joseph 5. Klein, Glencoe, El., assignor to Fiber Bond Corporation, a corporation of illinois Filed Aug. 5, 1957, Ser. No. 676,278 Claims. (Cl. 18S-49) This invention relates to an air filter and is particularly concerned with a self-sustaining deformable air filter that may be inserted into an opening of any shape and held therein lby frictional engagement with the walls of the opening.

The air filter of the present invention is particularly adapted for use with air conditioning or heating systems, and comprises an adhesively bonded fibrous web bonded to an open-work mesh backing which serves as a reinforcement and also helps the fibrous webretain its shape when it is deformed to fit in an opening in an air conditioning or heating system.

The web comprises a plurality of non-absorbent, nonmatting fibers, preferably plastic fibers, either straight or curled, of various lengths of from about one half inch to two inches, held in three-dimensional, random, arrangement by means of a iiexible adhesive. The individual fibers are first arranged in a three-dimensional, random arrangement and are then wetted lightly with adhesive to cause them to adhere to each other only at their spaced points of contact.

The adherence of the three-dimensional, randomly arranged fibers to each other at substantially only their points of contact imparts excellent air retaining and insulating qualities to the web. Air can pass readily through the web, but only at a very slow rate. The web may be shaped to fit around any object or to fit against the walls of an opening of any shape without losing its air retaining or insulating qualities.

Any adhesive which gives a iiexible bond may be used in accordance with the present invention, but an elastic adhesive such as natural or synthetic rubber deposited from a latex emulsion is preferred. A suitable synthetic rubber is a vulcanizable, rubbery copolymer of butadiene and acrylonitrile, for example, that sold by B. F. Goodrich Co. under the trademark Carbopol The web is bonded to an open work backing and reinforcement of self-sustaining deformable material such as wire mesh. The edge portions of the backing are bent upwardly so that the fibrous material faces outwardly, with its upstanding rim in contact with the Walls of the opening in which the filter is positioned.

A preferred illustrative embodiment of an air filter incorporating the above and other advantages is shown in the accompanying drawing, forming part of this specification, in which:

FIGURE l is a fragmentary perspective view of la conduit, which may be part of an air conditioning or heating system, with an air lter positioned therein;

FIG. 2 is a cross sectional view, taken along the line 2 2 of FIG. l;

FIG. 3 is a fragmentary plan view of the air filter; and

FIG. 4 is -a cross sectional view, taken along the line 4 4 of FIG. 3.

In the drawings, the reference numeral 2 indicates a backing of Wire mesh, resin coated open cloth such as tobacco cloth, screening cloth and the like, or other foraminated self-sustaining deformable material capable of holding any shape into which it is placed. The wire mesh or like foraminated material may have from 4 to 16 openings to the inch, preferably Within the range of from 4 to 8 openings to the inch.

A web 3 of three-dimensional, randomly arranged iibers is bonded to the Wire mesh backing. The fibers preferably are curled or crimped, but straight fibers of the same type may `be used. The fibers may be natural fibers, such as hogs hair, or they may be synthetic fibers such as nylon, rayon, acrylic fiber (a copolymer of vinyl chloride and acrylonitrile) commercially available under the trademark Orlon, or polyvinylidene chloride-polyvinyl chloride copolymer fiber, commercially available under the trademark Saran Nonorganic fibers such as glass fiber, commercially available under the trademark Fiberglas, may also be used. Any of these fibers may be used alone or mixed with each other.

The fibers are preferably of various lengths, from about one-half inch to two inches, and are intermingled in random arrangement so that they lay at various angles, both horizontally and vertically, to form a three-dimensional web with the individual fibers contacting each other at their separate points of contact throughout the web. Relatively few pairs of individual fibers contact at more than one point, and each fiber of the web contacts a plurality of other fibers at spaced points which may be in the same or in different planes.

The fibers are laid on the backing 2 in any suitable manner, and the web and backing are sprayed or otherwise coated lightly with an elastic adhesive on either one or both surfaces, preferably both surfaces. The amount of adhesive is sufficient to coat at least the outer fibers of the web so that they adhere to each other and to the backing at the points of contact only. The small amount of adhesive which passes through the interstices between the outer fibers Wets the underlying bers and causes them to adhere at their points of contact. The amount of adhesive is not sufficient to fill the voids between the fibers. It is not essential that the adhesive reach bers in the center of the web because the adhesive serves to tie the Whole Web together by joining fibers extending transversely of the web with the longitudinally extending fibers at both ends of the transversely extending fibers.

Any elastic adhesive material such as natural rubber, synthetic rubber, or adhesive resinous or other plastic material may be used. The adhesive material may be applied in solution or in emulsion form. In the case of either natural or synthetic rubber, for example, it is applied in the form of an aqueous suspension or latex, with or without vulcanizing agents, and the adhesive coating is then dried to precipitate the rubber. Any conventional, commercially available, ammonium-stabilized, natural rubber latex may be used in accordance with my invention, alone or in combination with a synthetic rubber latex. A suitable synthetic rubber latex which may be used as the adhesive is the rubbery copolymer of butadiene and acrylonitrile sold under the trademark CarbopoL If desired, there may be incorporated into the natural rubber latex or the mixed natural and synthetic rubber latex small amounts, about 0.25 to 3.0%, of a resin which serves to add quick tack and strength to the adhesive. Examples of resinous adhesives that may be used include solutions olf polyvinyl chloride or polyvinyl acetate or copolymers thereof in organic solvents.

The adhesive applied to the :fibers and the backing is dried to a non-tacky state, either naturally or artificially, rWithout compacting the web. This prevents the adhesive coating on any fiber from adhering to any other fiber, or to the backing, except at the points where the fibers are in contact with each other and the backing, -in the uncompressed, three-dimensional, random arrangement in which the Web is initially for-med. This arrangement forms innumerable intercommunicating voids in the Web so that air can pass through the web, but only at a relatively low rate. The vast number of voids or air spaces in the web makes the `structure eminently suitable for use as an air filter.

The filter, comprising the fibrous web and the openwork mesh backing to which it is adhered, may be eut into any desired shape, and is self-sustaining and deformable, conforming readily to the contour of irregularly shaped objects. In FGS. 1 and 2 the filter is shown positioned in a rectangular duct 4 which constitutes part of an airconditioning or heating system. The edges of the filter are bent to `form an upstanding rim 5 which presses the fibrous web against the inner Wall surfaces of the duct 4. The bending of theedges of the filter may be facilitated by providing cuts into the filter at the corners. Due to the yieldable, deformable character of the fibrous web, it conforms to the surface irregularities of the duct, thereby providing an effective edge seal against egress of air about the peripheral edges ofthe filter.

Preferably the fibrous web 3 is on the `outside of the foraminated backing 2, as shown in FIG. 2, so that when the filter is positioned in the duct the fibrous Web is in contact with the inner wall surfaces of the duct and is held in frictional contact with the Wall surfaces by the backing material. The deformability lof the foraminated backing material makes it capable of frictionally holding the yieldable, deformable fibrous web againstY the wall surfaces to provide an eicient seal Varound the edges of the filter regardless of the specific cross sectional shapev of the opening in which it is positioned. The backing also provides mechanical reinforcement for the fibrous Web.

Although I have described a preferred embodiment of the invention in considerable detaiLit will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details may be modified or changed Without departing from the spirit or scope of the invention. Accordingly, l do not desire to Vbe restricted to the exact construction described.

I claim:

1. A self-sustaining, deformable air lter comprising a self-sustaining, deformable, foraminated backing material and a porous fibrous web, .said :filter being deformed to provide an integralrim extending atan angle to the plane of the major portion of the filter, one Youter' surface of said fibrous web being adhesively bondedto one surface of said backing material, said fibrous web being held in said deformed shape by the adhesive bond between said one outer surface of said web and said backing material.

2. A self-sustaining, deformable filter ycomprising a self-sustaining, deformable, foraminated backing material and a porous fibrous web adhered thereto, said filter being shaped to iit an opening and deformed to provide an integral rim extending at an angle to the plane of the major portion of said filter, said rim being adapted to press said fibrous web into frictional engagement with the Wall surfaces defining said opening.

3. A self-sustaining, deformable filter oomprising a self-sustaining, deformable, open mesh backing material and a porous brous web adhesively bonded thereto, said filter being shaped to fit an opening'and deformed to pro vide an integral rim extending at an angle to the plane of the major portion of said filter and adapted to engage the wall surfaces defining said opening with the fibrous -Web in frictional engagement with said wall surfaces.

4. A self-sustaining, deformable, foraminated material and a porous fibrous web secured thereto, the major portions of said deformable material and said web lying in parallel planes, a portion of said foraminated deformable material being shaped tofit an opening and deformed to provide a rim extending approximately per--V pendicular to the plane of the major portion of said de` formable material with said fibrous web on the outer surface of said rim, said rim being adapted to hold the fibrous Web on the outer surface of said rim in frictional engagement With the surfaces defining said opening.

5. A self-sustaining,deformable, open mesh material and a porous, yieldable and deformable web of fibers in random three-dimensional arrangement, said fibers being adhesively bonded to each other and to said deformable Y material only at spaced points of contact, said open mesh deformable material being shaped to fit an opening and deformed to provide a rim extending approximately perpendicular to the plane of the Vmajor portion of said deformable material with the fibrous web on the outer surface thereof, said rim being adapted to hold said fibrous web in frictional engagement with the surfaces deniug said opening.

References Cited in the file of this patent UNlTED YSTATES PATENTS 1,886,460 Anderson Oct. 12, 1931 2,124,370 Gaarder July 19, 1938 2,389,435 Karlstrom Nov. 20, 1945 2,505,175 Davis Apr. 25, 1950 2,521,985 Lan-g et al. Sept. 12, 1950 2,582,915 Sebok Jan. 15, 1952 2,685,345 Lindner Aug. 3, 1954 2,784,132 Maisel Mar. 5, 1957 2,835,341 Parker May 20, 1958 

